is this true? you need an i7 for crossfire.. sorta

[adamknox]

Just been reading up on the diffrence between i7 and Phenom 2 and i read a poster say "phenom 2 = 1 gpu. i7 = crossfire/sli) he went on to say about to get the full effect of a crossfire you NEED an i7 as amd (he says the 965 model) is **** when crossfireing/sli'ing. Never heard of that but is there any truth in it?...

 

[Rroff]

Depends a lot on the setup...

i.e. 2x 5870 in crossfire would almost deffinatly be bottlenecked in some cases by a stock i7 or even a Phenom II at 3.6gig, whereas a couple of 5770 in CF would probably be fine on a well clocked Phenom II.

TBH tho a lot of the cases where you can really see the Phenom II fall down are quite synthetic i.e. 1024x768 with tri-SLI GTX285 or something similiar which your never gonna run into in day to day use, the main reason to go for the i7 is for the better overclocking potential which will ensure your getting the MHz to push the setup.

 

[adamknox]

Depends a lot on the setup...

i.e. 2x 5870 in crossfire would almost deffinatly be bottlenecked in some cases by a stock i7 or even a Phenom II at 3.6gig, whereas a couple of 5770 in CF would probably be fine on a well clocked Phenom II.

TBH tho a lot of the cases where you can really see the Phenom II fall down are quite synthetic i.e. 1024x768 with tri-SLI GTX285 or something similiar which your never gonna run into in day to day use, the main reason to go for the i7 is for the better overclocking potential which will ensure your getting the MHz to push the setup.

*chin wabbles* Soooo... i could never crossfire my 5870 with my 955? ..... any one wana buy my 955 and mobo for £150 in that case lol!

 

[Rroff]

I wouldn't say never... in games like crysis you'd see massive gains... in some cases you might lose say 30% off the top but that would be the minority rather than majority.

 

[Technics]

I hope this isn't totally true, i plan to run crossfire 5770's on a phenom II :S

 

[drunkenmaster]

No, whoever told you that is a complete tool, in most gaming situations theres very little difference, the only times you'll see the difference will be in non gpu limited situations, the whole point of getting extra gpu's, is to run a heavier gpu load, so the question remains, why aren't you running at your gpu's limits, if you've paid for them. Answer is, you don't, no matter what GPU setup you have you'll be basically gpu limited.

IF you have a 4350 and game at 1024x768 with low settings, you're gpu limited, if you run a 5870 at 1920x1200 at high settings, you're gpu limited, if you run a triple sli or quadfire set up, you'll likely be using a 30" screen, or with AMD these days, eyefinity and a humougous res, and therefore again be gpu limited.

You'd notice a difference between a P2 and an i7, if you run 4x5870's at 1680x1050, but why would you buy 4 gpu's to run that res?

I've seen one review to date suggesting you MUST have a i7 for crossfire, it used a i7 quad, against a penryn based DUAL CORE< and called it a fair test but argued the increased performance was all down to architecture, and how SLI/xfire simply worked better with the new architecture.

ANy sane testing and you'd see little to no difference, in all but the most rare and obscure of titles.

 

[Rroff]

Its not completely without merit... when people were benchmarking GTX260 SLI setups on these forums my then setup Q6600 @ 3.6gig against the Phenom II X4 940 @ 3.2gig - identical GPU setup and settings in the lost coast benchmark I was almost doubling their fps... whereas in crysis there was nothing in it.

Theres a small number of cases where the Phenom II falls down, most of the time as I said its fine.

 

[Martini1991]

And people always seem to run there PII at stock NB/HT.

 

[daniel_bourton]

also there is cases the i7 in gaming has not been the best and the pii scraps some mnor fps over it but it will be fine.
also AMD are partners of ATI so they would have fought about the crossfire situation closely espacialy when they advertise the **** out of fusion systems.

 

[Rroff]

also there is cases the i7 in gaming has not been the best and the pii scraps some mnor fps over it but it will be fine.
also AMD are partners of ATI so they would have fought about the crossfire situation closely espacialy when they advertise the **** out of fusion systems.

Interestingly if you look at the official ATI crossfire benchmarks - they almost always use i7 setups for pure synthetic multiGPU benchmarking they are by far the strongest performers - specially once your past 4gig.

For every day gaming theres not much in it, there are some situations where the PII falls down but most of the time its up there.

 

[buttkinz]

And people always seem to run there PII at stock NB/HT.

good point there, when overclocked with NB at stock it sux, as soon as the NB is overclocked it runs a lot better, in crysis i made about 40% higher fps from upping the NB, maybe something to do with the mobo but im sure its not.
so many review sites dont know about overclocking the phenoms NB

an overclocked phenom is fine for 5770's, running fine here

 

[Rroff]

I think its more todo with finding the optimal ratios than just NB/HT overclocking increases performance - off the top of my head I believe theres certain frequencies where the HT gives optimal performance at and just a few MHz either side can lose you quite a bit.

 

[buttkinz]

ahh yes, i remeber a chart that someone had and they tested superpi etc at the different combinations, il try and dig it out...

edit: heres the page
http://www.overclockers.com/the-importance-of-northbridge-overclocking-with-the-phenom-ii/

 

[Squark]

ahh yes, i remeber a chart that someone had and they tested superpi etc at the different combinations, il try and dig it out...

edit: heres the page
http://www.overclockers.com/the-importance-of-northbridge-overclocking-with-the-phenom-ii/

From those charts I'd say it looks best to have the NB at ~2000MHz all the time

 

[buttkinz]

not when overclocked i run 2600mhz for 3.7-3.8ghz core speeds,, check the scores again for overclocked speeds

 

[HangTime]

There is no right or wrong answer to this, essentially all you need to ask yourself is "Bearing in mind my maximum screen resolution, and the type of games I like to play, am I likely to be CPU limited?".

So for example if you are into RTS games, and have a relatively small screen, then yes you are probably better off looking at i7.

The good thing about CPU bottlenecks is that often you can reduce the impact but increasing the amount of AA, i.e. increasing the load on the GPU(s).

 

[Squark]

Argh I think my brain might have died, I'm reading the charts totally differently now

Anyway, my Phenom1 currently has a NB freq of 2300MHz

I'd like a PhII but I cant afford the outlay at the mo

 

[GunsAkimbo]

The good thing about CPU bottlenecks is that often you can reduce the impact but increasing the amount of AA, i.e. increasing the load on the GPU(s).

'scuse me for being a newb.... but does that ^^ solution only make the CPU bottle neck seem less severe by exaggerating and/or creating a GPU bottleneck.

To me it seems akin to saying you only need 4mb or ram to run Crysis because if you insert a live hand-grenade, sans-pin, into your system the resulting explosion will make the 4mb of ram the least of your problems

Of course I kid, no offence, but please explain because I'm WAY out of touch if layering on AA actually can make things run faster ??

 

[Rroff]

If the bottleneck is due to the CPU being unable to feed the GPU data fast enough - turning up the AA means the GPU has something to do while waiting on the CPU - so you get nicer filtering instead of just losing a lot of fps anyhow.

 

[GunsAkimbo]

Thats not "reducing impact" though its giving the GPU "busy-work", nice looking "busy-work"

Thanks for the explanation though makes more sense when put like that.